Fin whale

The fin whale (Balaenoptera physalus), also called the finback whale, razorback, or common rorqual, is a marine mammal belonging to the suborder of baleen whales. It is the second longest animal in the world and second largest rorqual after the blue whale,[7] growing to over 27 metres (89 ft) long[8] and weighing nearly 74 tonnes (73 long tons; 82 short tons).[9] The AmericannaturalistRoy Chapman Andrews called the fin whale "the greyhound of the sea... for its beautiful, slender body is built like a racing yacht and the animal can surpass the speed of the fastest ocean steamship."[10]

Long and slender, the fin whale's body is brownish-grey with a paler underside. There are at least two recognized subspecies: the fin whale of the North Atlantic, and the fin whale of the Southern Hemisphere. It is found in all the world's major oceans, from polar to tropical waters. It is absent only from waters close to the ice pack at both the north and south poles and relatively small areas of water away from the open ocean. The highest population density occurs in temperate and cool waters.[11] Its food consists of small schooling fish, squid, and crustaceans including copepods and krill.

Like all other large whales, the fin whale was heavily hunted during the twentieth century and is an endangered species. Over 725,000 fin whales were reported taken from the Southern Hemisphere alone between 1905 and 1976 and there are now thought to be only 38,000 in that region (ref. to 1997).[2] The International Whaling Commission (IWC) has issued a moratorium on commercial hunting of this whale,[12] although Iceland and Japan have resumed hunting: in 2009 and 2010, Iceland took 125 and 148 fin whales, while Japan has taken eighteen fin whales in seven seasons (2005-12) of whaling in the Antarctic.[13][14][15] Iceland exported 500- 600 tons of fin whale meat to Japan in 2011[16], worth 486,189,000 ISK ($3.8 million).[17] The species is also hunted by Greenlanders under the Aboriginal Subsistence Whaling provisions of the IWC. Estimates suggest that the population of the remaining fin whales in the world's seas range from less than 100,000 to roughly 119,000.[2][18] Collisions with ships and noise from human activity also significantly threaten recovery.

As of 2006, there are two named subspecies, each with distinct physical features and vocalizations. The Northern fin whale, B. p. physalus (Linnaeus 1758), inhabits the North Atlantic, and the Southern fin whale, B. p. quoyi (Fischer 1829), occupies the Southern Ocean.[23] Most experts consider the fin whales of the North Pacific to be a third, as yet unnamed subspecies.[11] The three groups mix at most rarely.[citation needed]

Hybridization

The blue and fin whale have been described as genetically distant as a gorilla and human [24] (or 3.5 million years on the evolutionary tree[25]). Nevertheless, hybrid individuals between blue and fin whales with characteristics of both is known to occur with relative frequency in the North Atlantic[26] and in the North Pacific.[27]

A pair of researchers who reported the DNA profile of sampling of whale meat in the Japanese market found evidence of blue/fin hybrid meat.[28]

The fin whale is usually distinguished by its tall spout, long back, prominent dorsal fin, and asymmetrical coloration. In the Northern Hemisphere, the average size of adult males and females is about 18.5 m (60 ft) and 20 m (65 ft), while in the Southern Hemisphere it is 20.5 m (67 ft) and 22 m (72 ft).[31] In the North Atlantic, the longest reported was 24.5 m (80' 6" ft) (albeit what whalers' called a "bastard", a possible blue/fin hybrid), while the longest measured by True (1904) was 21.5 m (70' 8" ft), both females. In the North Pacific, the longest reported were 22.9 m (75 ft) for males and 24.7 m (81 ft) for females, while the longest reliably measured were 20.8 m (68 ft) and 22.9 m (75 ft), respectively.[32] In the Southern Hemisphere, the longest reported for each sex were 25 m (82 ft) and 27.3 m (89' 6" ft), while the longest measured by Mackintosh and Wheeler (1929) were 22.4 m (73' 7" ft) and 24.5 m (80' 5" ft);[8] although Major F. A. Spencer, while whaling inspector of the factory ship Southern Princess (1936-38), confirmed the length of a 25.9 m (85 ft) female caught in the Antarctic south of the southern Indian Ocean.[33] The largest fin whale ever weighed (piecemeal) was a 22.7 m (74.5 ft) pregnant female caught by Japanese whalers in the Antarctic in 1948 which weighed 69.5 tonnes (68.4 long tons; 76.6 short tons), minus 6% for loss of fluids during the flensing process.[9] It is estimated that an individual over 27 m (89 ft) would weigh in excess of 120 tonnes (120 long tons; 130 short tons). Full physical maturity is attained between 25 and 30 years. Fin whales live to 94 years of age,[34] although specimens have been found aged at an estimated 135–140 years.[35] A newborn fin whale measures about 6.5 metres (21 ft) in length and weighs approximately 1,800 kilograms (4,000 lb).[36] The animal's large size aids in identification, and it is usually only confused with the blue whale, the sei whale, or, in warmer waters, Bryde's whale.

The fin whale is brownish to dark or light gray dorsally and white ventrally. It has paired blowholes on a prominent splashguard, and a broad, flat V-shaped rostrum. Two lighter-colored chevrons radiate from the eyes and curve forward, joining to form a V-shape oriented towards the head.[18] Its lower jaw (and occasionally upper jaw) is white, while the left side of the jaw is gray or black.[18] This type of asymmetry is seen in Omura's whale and occasionally in minke whales. It was hypothesized to have evolved because the whale swims on its right side when surface lunging and it often circles to the right while at the surface above a prey patch. However, the whales just as often circle to the left. There is no accepted hypothesis to explain the asymmetry.[37]

The whale has a series of 56–100 pleats or grooves along the bottom of the body that run from the tip of the chin to the navel that allow the throat area to expand greatly during feeding. It has a curved, prominent 60 centimetres (24 in) dorsal fin about three-quarters of the way along the back. Its flippers are small and tapered, and its tail is wide, pointed at the tip, and notched in the centre.[18]

When the whale surfaces, the dorsal fin is visible soon after the spout. The spout is vertical and narrow and can reach heights of 6 metres (20 ft) or more.[18] When feeding, they will blow 5-7 times in quick succession, but while traveling or resting will blow a single time every minute or two. On their terminal (last) dive they arch their back high out of the water, but rarely raise their flukes out of the water. It then dives to depths of up to 470 metres (1,540 ft) when feeding or only a few hundred feet when resting or traveling. The average feeding dive off California and Baja lasts 6 minutes, with a maximum of 17 minutes; when traveling or resting they usually dive for only a few minutes at a time.[38] Fin whales rarely breach.[18]

The fin whale is one of the fastest cetaceans and can sustain speeds of 37 kilometres per hour (23 mph)[36] and bursts in excess of 40 kilometres per hour (25 mph) have been recorded, earning the fin whale the nickname "the greyhound of the sea".[39] Fin whales are more gregarious than other rorquals, and often live in groups of 6–10, although feeding groups may reach up to 100 animals.[34]

Life history

Mating occurs in temperate, low-latitude seas during the winter, followed by an eleven months to one year gestation period. A newborn weans from its mother at 6 or 7 months of age when it is 11 metres (36 ft) to 12 metres (39 ft) in length, and the calf accompanies the mother to the summer feeding ground. Females reproduce every 2 to 3 years, with as many as 6 fetuses being reported, but single births are far more common. Females reach sexual maturity at between 6 and 12 years of age at lengths of 17.7-19 m (58-62.5 ft) in the Northern Hemisphere and 20 m (65 ft) in the Southern Hemisphere.[31]

Predation

The only known predator of the fin whale is the killer whale, with at least twenty eyewitness and second-hand accounts of attack or harassment. They usually flee and offer little resistance to attack. Only a single confirmed fatality has occurred: in October 2005, sixteen killer whales attacked and killed a fin whale in the Canal de Ballenas, Gulf of California, after chasing it for about an hour. They fed on its sinking carcass for about 15 minutes before leaving the area. In July 1908, a whaler reportedly saw two killer whales attack and kill a fin whale off western Greenland. In January 1984 seven were seen from the air circling, holding the flippers, and ramming a fin whale in the Gulf of California, but the observation ended when darkness set in.[43][44]

It feeds by opening its jaws while swimming at a relatively high speed, 11 kilometres per hour (6.8 mph) in one study,[47] which causes it to engulf up to 70 cubic metres (18,000 US gal; 15,000 imp gal) of water in one gulp. It then closes its jaws and pushes the water back out of its mouth through its baleen, which allows the water to leave while trapping the prey. An adult has between 262 and 473 baleen plates on each side of the mouth. Each plate is made of keratin that frays out into fine hairs on the ends inside the mouth near the tongue. Each plate can measure up to 76 centimetres (30 in) in length and 30 centimetres (12 in) in width.[7] The whale routinely dives to depths of more than 200 metres (660 ft) where it executes an average of four "lunges", where it feeds on aggregations of krill. Each gulp provides the whale with approximately 10 kilograms (22 lb) of krill.[47] One whale can consume up to 1,800 kilograms (4,000 lb) of food a day,[7] leading scientists to conclude that the whale spends about three hours a day feeding to meet its energy requirements, roughly the same as humans. If prey patches are not sufficiently dense, or are located too deep in the water, the whale has to spend a larger portion of its day searching for food.[47] One hunting technique is to circle schools of fish at high speed, frightening the fish into a tight ball, then turning on its side before engulfing the massed prey.[7]

Like other whales, the male fin whale makes long, loud, low-frequency sounds.[36] The vocalizations of blue and fin whales are the lowest-frequency sounds made by any animal.[48] Most sounds are frequency-modulated (FM) down-swept infrasonic pulses from 16 to 40 hertz frequency (the range of sounds that most humans can hear falls between 20 hertz and 20 kilohertz). Each sound lasts one to two seconds, and various sound combinations occur in patterned sequences lasting 7 to 15 minutes each. The whale then repeats the sequences in bouts lasting up to many days.[49] The vocal sequences have source levels of up to 184–186 decibels relative to 1 micropascal at a reference distance of one metre, and can be detected hundreds of miles from their source.[50]

When fin whale sounds were first recorded by US biologists, they did not realize that these unusually loud, long, pure and regular sounds were being made by whales. They first investigated the possibilities that the sounds were due to equipment malfunction, geophysical phenomena, or even part of a Soviet Union scheme for detecting enemy submarines. Eventually, biologists demonstrated that the sounds were the vocalizations of fin whales.[48]

Direct association of these vocalizations with the reproductive season for the species and that only males make the sounds point to these vocalizations as possible reproductive displays.[51][52] Over the past 100 years, the dramatic increase in ocean noise from shipping and naval activity may have slowed the recovery of the fin whale population, by impeding communications between males and sexually receptive females.[53]

Range and habitat

Aerial view of a fin whale, showing V-shaped chevron

Like many large rorquals, the fin whale is a cosmopolitan species. It is found in all the world's major oceans, and in waters ranging from the polar to the tropical. It is absent only from waters close to the ice pack at both the north and south extremities and relatively small areas of water away from the large oceans, such as the Red Sea and the Baltic Sea. The highest population density occurs in temperate and cool waters. It is less densely populated in the warmest, equatorial regions. It prefers deep waters beyond the continental shelf to shallow waters.[citation needed]

The North Atlantic fin whale has an extensive distribution, occurring from the Gulf of Mexico and Mediterranean Sea, northward to the edges of the Arctic ice pack. In general, fin whales are more common north of approximately 30°N latitude, but considerable confusion arises about their occurrence south of 30°N latitude because of the difficulty in distinguishing fin whales from Bryde's whales.[54] Extensive ship surveys have led researchers to conclude that the summer feeding range of fin whales in the western North Atlantic was mainly between 41°20'N and 51°00'N, from shore seaward to the 1,000 fathoms (1,800 m) contour.[55]

Summer distribution of fin whales in the North Pacific is the immediate offshore waters from central Baja California to Japan, and as far north as the Chukchi Sea bordering the Arctic Ocean.[56] They occur in high densities in the northern Gulf of Alaska and southeastern Bering Sea between May and October, with some movement through the Aleutian passes into and out of the Bering Sea.[57] Several whales tagged between November and January off southern California were killed in the summer off central California, Oregon, British Columbia, and in the Gulf of Alaska.[56] Fin whales have been observed feeding 250 miles south of Hawaii in mid-May, and several winter sightings have been made there.[58] Some researchers have suggested that the whales migrate into Hawaiian waters primarily in the autumn and winter.[59]

Although fin whales are certainly migratory, moving seasonally in and out of high-latitude feeding areas, the overall migration pattern is not well understood. Acoustic readings from passive-listening hydrophone arrays indicate a southward migration of the North Atlantic fin whale occurs in the autumn from the Labrador-Newfoundland region, south past Bermuda, and into the West Indies.[60] One or more populations of fin whales are thought to remain year-round in high latitudes, moving offshore, but not southward in late autumn.[60] In the Pacific, migration patterns are poorly characterized. Although some fin whales are apparently present year-round in the Gulf of California, there is a significant increase in their numbers in the winter and spring.[61] Southern fin whales migrate seasonally from relatively high-latitude Antarctic feeding grounds in the summer to low-latitude breeding and calving areas in the winter. The location of winter breeding areas is still unknown, since these whales tend to migrate in the open ocean.[11]

Population and trends

A frontal view of a fin whale, showing asymmetrical coloration

Poor understanding of migration patterns combined with contradictory population surveys makes estimating the historical and current population levels of the whale difficult and contentious. Due to a long history of hunting this whale, pre-exploitation population levels are difficult to determine.[citation needed]

North Atlantic

North Atlantic fin whales are defined by the International Whaling Commission to exist in one of seven discrete population zones: Nova Scotia-New England, Newfoundland-Labrador, western Greenland, eastern Greenland-Iceland, North Norway, West Norway-Faroe Islands, and Ireland-Spain-United Kingdom-Portugal. Results of mark-and-recapture surveys have indicated that some movement occurs across the boundaries of these population zones, suggesting that each zone is not entirely discrete and that some immigration and emigration does occur.[55] J. Sigurjónsson estimated in 1995 that total pre-exploitation population size in the entire North Atlantic ranged between 50,000 and 100,000 animals,[62] but his research is criticized for not providing supporting data and an explanation of his reasoning.[11] In 1977, D.E. Sergeant suggested a "primeval" aggregate total of 30,000 to 50,000 throughout the North Atlantic.[63] Of that number, about 8,000 to 9,000 would have resided in the Newfoundland and Nova Scotia areas, with whales summering in U.S. waters south of Nova Scotia presumably omitted.[11][64] J.M. Breiwick estimated that the "exploitable" (above the legal size limit of ft50) component of the Nova Scotia population was 1,500 to 1,600 animals in 1964, reduced to only about 325 in 1973.[65] Two aerial surveys in Canadian waters since the early 1970s gave numbers of 79 to 926 whales on the eastern Newfoundland-Labrador shelf in August 1980,[66] and a few hundred in the northern and central Gulf of Saint Lawrence in August 1995–1996.[67] Summer estimates in the waters off western Greenland range between 500 and 2,000,[68] and in 1974, Jonsgard considered the fin whales off Western Norway and the Faroe Islands to "have been considerably depleted in postwar years, probably by overexploitation".[69] The population around Iceland appears to have fared much better, and in 1981, the population appeared to have undergone only a minor decline since the early 1960s.[70] Surveys during the summers of 1987 and 1989 estimated of 10,000 to 11,000 between eastern Greenland and Norway.[71] This shows a substantial recovery when compared to a survey in 1976 showing an estimate of 6,900, which was considered to be a "slight" decline since 1948.[72] A Spanish NASS survey in 1989 of the France-Portugal-Spain sub-area estimated a summer population range at 17,355.[73] The aggregate population level is estimated to be between 40,000[74] and 56,000[26] individuals.

North Pacific

The total historical North Pacific population was estimated at 42,000 to 45,000 before the start of whaling. Of this, the population in the eastern portion of the North Pacific was estimated to be 25,000 to 27,000.[75] By 1975, the estimate had declined to between 8,000 and 16,000.[76][77] Surveys conducted in 1991, 1993, 1996, and 2001 produced estimates of between 1,600 and 3,200 off California and 280 to 380 off Oregon and Washington.[78] The miniumum estimate for the California-Oregon-Washington population, as defined in the U.S. Pacific Marine Mammal Stock Assessments: 2005, is about 2,500.[79] Surveys in coastal waters of British Columbia in summers 2004 and 2005 produced abundance estimates of approximately 500 animals (95% confidence intervals: 201-1,220).[80] Surveys near the Pribilof Islands in the Bering Sea indicated a substantial increase in the local abundance of Fin Whales between 1975–1978 and 1987–1989.[81] In 1984, the entire population was estimated to be at less than 38% of its historic carrying capacity.[40]

Antarctica

Relatively little is known about the historical and current population levels of the Southern fin whale. The IWC officially estimates that the Southern Hemisphere pre-whaling population was 400,000 whales, and that the population in 1979 (at the cessation of Antarctic large scale whaling) was 85,200.[82] Both the current and historical estimates should be considered as poor estimates because the methodology and data used in the study are known to be flawed.[11] Other estimates cite current size to be between 15,000 (1983) and 38,000 (1997).[2] As of 2006, there is no scientifically accepted estimate of current population or trends in abundance.[11]

Human interaction

"The Finback" (Balaenoptera velifera, Cope) from Charles Melville Scammon's Marine Mammals of the North-western coast of North America (1874)

In the 19th century, the fin whale was occasionally hunted by open-boat whalers, but it was relatively safe because of its speed and the fact that it often sank when killed. However, the later introduction of steam-powered boats and harpoons that exploded on impact made it possible to kill and secure them along with blue whales and sei whales on an industrial scale. As other whale species became over-hunted, the whaling industry turned to the still-abundant fin whale as a substitute.[83] It was primarily hunted for its blubber, oil, and baleen. Approximately 704,000 fin whales were caught in Antarctic whaling operations alone between 1904 and 1975.[84]

The introduction of factory ships with stern slipways in 1925 substantially increased the number of whales taken per year. In 1937-38 alone, over 29,000 fin whales were taken. From 1953-54 to 1961-62, the catch averaged over 30,000 per year. By 1962-63, sei whale catches began to increase as fin whales became scarce. By 1975-76, fewer than 1,000 fin whales were being caught each year. In the North Pacific, over 74,000 fin whales were caught between 1910 and 1975.[85] Between 1910 and 1989, over 55,000 were caught in the North Atlantic.[86]

The IWC prohibited hunting in the Southern Hemisphere in 1976.[84] The Soviet Union engaged in the illegal killing of protected whale species in the North Pacific and Southern Hemisphere, over-reporting fin whale catches to cover up illegal takes of other species. In the North Pacific, they reported taking over 10,000 fin whales between 1961-79, while the true catch was less than 9,000. In the Southern Hemisphere, they reported taking nearly 53,000 between 1948-73, when the true total was a little over 41,000.[87][88][89] The fin whale was given full protection from commercial whaling by the IWC in the North Pacific in 1976, and in the North Atlantic in 1987, with small exceptions for aboriginal catches and catches for research purposes.[36] All populations worldwide remain listed as endangered species by the US National Marine Fisheries Service and the International Conservation UnionRed List, and the fin whale is on Appendix 1 of CITES.[2][90][91]

The IWC has set a quota of 19 fin whales per year for Greenland. Meat and other products from whales killed in these hunts are widely marketed within Greenland, but export is illegal. Iceland and Norway are not bound by the IWC's moratorium on commercial whaling because both countries filed objections to the moratorium.[11] In October 2006, Iceland's fisheries ministry authorized the hunting of nine fin whales through August 2007.[92] In 2009 and 2010, Iceland caught 125 and 148 fin whales, respectively.[93]

In the southern hemisphere, Japan permits annual takes of 10 fin whales under its Antarctic Special Permit whaling program for the 2005–2006 and 2006–2007 seasons.[94] The proposal for 2007–2008 and the subsequent 12 seasons allows taking 50 per year.[11] While ten fin whales were caught in the 2005-06 season and three in the 2006-07 season, none were caught in the 2007-2008 season. A single fin whale was caught in both the 2008-09 and 2009-10 seasons, two were taken in the 2010-11 season, and one was taken in the 2011-12 season.[95]

Collisions with ships are a major cause of mortality. In some areas, they cause a substantial portion of large whale strandings. Most serious injuries are caused by large, fast-moving ships over or near the continental shelf.[96]

Conservation

The Fin whale is listed on both Appendix I[105] and Appendix II[105] of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix I[105] as this species has been categorized as being in danger of extinction throughout all or a significant proportion of their range and CMS Parties strive towards strictly protecting these animals, conserving or restoring the places where they live, mitigating obstacles to migration and controlling other factors that might endanger them and also on Appendix II[105] as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. In addition, Fin whale is covered by the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS) and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MOU).

^Andrews, Roy Chapman. 1916. Whale hunting with gun and camera; a naturalist's account of the modern shore-whaling industry, of whales and their habits, and of hunting experiences in various parts of the world. New York: D. Appleton and Co., p. 158.

^A. Arnason and A. Gullberg (1993). "Comparison between the complete mtDNA sequences of the blue and fin whale, two species that can hybridize in nature". Journal of Molecular Ecology37 (4): 312–322. PMID8308901.

^Mead, J.G. (1977). "Records of Sei and Bryde's whales from the Atlantic Coast of the United States, the Gulf of Mexico, and the Caribbean". Rep. Int. Whal. CommnSpec. Iss. 1: 113–116. ISBN0-906975-03-4.

^Breiwick, J.M. (1993). Population dymanics and analyses of the fisheries for fin whales (Balaenoptera physalus) in the northwest Atlantic Ocean. (Ph.D. thesis) University of Washington, Seattle. 310 pp..

^ abcd"Appendix I and Appendix II" of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). As amended by the Conference of the Parties in 1985, 1988, 1991, 1994, 1997, 1999, 2002, 2005 and 2008. Effective: 5th March 2009.